Contact lenses made from silicone hydrogels are rapidly gaining popularity over contact lenses made from conventional hydrogel materials because, like conventional hydrogel lenses, they are comfortable to wear, but they have the added advantage of having higher oxygen permeability, which is believed to be healthier for the eye. However, contact lenses made from silicone hydrogels often have physical properties that make them more difficult to process during manufacturing, and typically the lenses need to be extracted in volatile organic solvents to achieve acceptable surface wettability and good dimensional stability. The use of volatile organic solvents in manufacturing presents safety and environmental concerns and adds costs to the manufacturing process.
New formulations of silicone hydrogel contact lenses that can be manufactured without the use of volatile organic solvents, and that result in dimensionally stable contact lenses having ophthalmically-acceptable surface wettabilities are desired.
Some patent documents describing silicone hydrogel contact lenses include U.S. Publ. No. 2007/0296914, U.S. Publ. No. 2007/0066706, U.S. Publ. No. 2007/0231292, U.S. Pat. No. 5,965,631, WO 2011/041523, U.S. Pat. No. 5,358,995, European Publ. No. 1870736A1, U.S. Publ. No. 2006/063852, U.S. Publ. No. 2011/0009587, and U.S. Publ. No. 2009/0234087.